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An encapsulated helical one-dimensional cobalt iodide nanostructure


Single-walled carbon nanotubes (SWNTs) can be used as templates for the growth of low-dimensional inorganic materials whose structures and properties often differ greatly from those of the bulk1. Here we describe the detailed crystallography of an entire helical one-dimensional cobalt diiodide nanostructure encapsulated within a SWNT. This material has an unprecedented twisted double tetrahedral chain structure arising from a rotation of Co2I4 units along its length. The complete nanostructure comprises two distinct regions with oppositely handed helices separated by a short disordered region. The encapsulating SWNT shows a commensurate ovoid distortion reflecting an unexpectedly strong interaction between the nanostructure and the SWNT.

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Figure 1: Detailed structure of the encapsulated CoI2 nanostructure.
Figure 2: Overall helical structure of the encapsulated CoI2 nanostructure.
Figure 3: End-on views of a space-filling model with atoms represented by spheres according to their size.


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We acknowledge financial support from EPSRC, The Royal Society and the Leverhulme Trust.

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Correspondence to Jeremy Sloan or Angus I. Kirkland.

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The authors declare no competing financial interests.

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Philp, E., Sloan, J., Kirkland, A. et al. An encapsulated helical one-dimensional cobalt iodide nanostructure. Nature Mater 2, 788–791 (2003).

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